1. Field of the Invention
The present invention relates to a fall prevention system. More specifically, the present invention is concerned with a security system for preventing persons from falling when climbing a pylon, tower, mast or the like for maintenance or any other purpose.
2. Brief Description of the Prior Art
The prior art fall prevention systems presently in operation and presently available on the market are made of metal such as stainless steel or aluminum.
As well known to those of ordinary skill in the art, television broadcasting requires a vertical antenna 20-200 feet high mounted at the top of a tower 100-1500 feet high. These top mount antenna have a radiation pattern of 360.degree. and radiates radio-frequency (RF) waves at powers as high as 10 kW-500 kW depending on the area to be covered.
As RF waves propagating through the air are reflected by pieces of metal, including stainless steel and aluminium, a prior art metallic fall prevention system installed onto a top mount antenna will reflect the RF waves and return these waves to the antenna to thereby cause a distortion of the radiation pattern and thereby greatly reduce the efficiency of the top mount antenna.
Accordingly, in 80% of the television broadcasting antenna installations presently in operation, a fall prevention system is provided on the tower between the ground and the top mount antenna. For the above reasons, metallic fall prevention systems have never been installed onto the top mount antenna.
Other types of ropes, made for example of nylon, polypropylene, etc., are also available on the market to construct fall prevention systems. Unfortunately, these ropes do not resist to ultraviolet (UV) rays and to RF radiation. They also allow water to infiltrate therein. As the top mount antennae radiate a high concentration of RF waves, such ropes would deteriorate very quickly to result into a non reliable and dangerous fall prevention system.
Another alternative is to install a temporary fall prevention system. The drawback of this alternative is that the worker will benefit no protection during installation and dismantlement such a temporary fall prevention system. Dismantlement is required since steel installations will reflect radio-frequency waves while nylon and polypropylene ropes will deteriorate by exposure to the RF radiation.